Electric engraving apparatus.



A. M ROBINSON.

ELECTRIC ENGHAVING APPARATUS.

APPLICATION FILED JAN. 28. 1913.

1,289,000, Patented Dec. 2%, 1918.

2 SHEETSSHEET I.

A. M. ROBINSON.

ELECIRIC ENGRAVING APPARATUS.

APPLICATION FILED JAN. 28. 1818.

1,289,000. lutunml m. 2L, 1915.

2 SHEETSSHEET 2.

WOR K 29 EIIIIIH I i IN VE'N TOP? n A TTORNEV ments in' Electric Engraving Apparatus, of

- which the following is a specification.

UNITED STATES PATENT OFFICE. I ANDRE-W'M. nonmsoiv, or PaovIiJENoE, RHODE' IsLANiD, A ssie-Noa'ro R..I. "ELEC-Q TRICAL INSTRUMENT 00., or rnovxnnncn, VBIEiO-D E snann, aconroaarxon or RHODE ISLAND.

ELECTRIC nNGaAv'ING. APPARATUS.

specification of Letters Patent. Patented Dec..24,:1 918.

Application Median nary 28, 191 8. -Serialli'o. 214,258.

Be it known that I, ANDREW M; ROBibISON,

of the city of Providence, .in the county of Providence and-State of Rhode Island, have.

This invention relates to an electric engraving apparatus employed for graduat-. ing tools'or otherwise marking metal parts, and the object of this invention is to provlde' such a marking apparatus with a transformer for producing the desired character of electric current to be applled to the. work,

.a work-support and an engraving pencil all connected in a main electric, clrcuiq' whereby when the point of the pencil is moved along'the surface of thework, the current in passing from the pencil through the work, scores or cuts the metal path traveled by the pencil.

A further object of the invention is to provide an auxiliary electric circuit also appended c'lalms.

connected to the pencil and means'injthe' pencil for controlling the making and break ing of the auxiliary circuit to open and. close the main circuit, so as to prevent arcing'atj r the pencil point when'ra'ised from'the work,

which arcing eflect pits-the work and is quite objectionable where work is desired.

With these and'other objects in view, theinvention consists of certain novel features.

of-constructiom aswill be more fully described, and particularly pointed out in the In the accompanying drawings I g, I Figure 1- is a perspective view of'my improved engraving apparatus, showing the same as adapted to beconta'ined within av a single portable receptacle.

- Fig. 2'is a diagrammatic view showing 2 the general arrangement of' the transformer and the switches .'for. controlling the flowof current the main circuit-therefrom;

' also showing the auxiliary circuit( as arranged to break the main circuit by operatin'g means carriedby the pencil.

Fig. 3 is a wiring diagram showing bot h themain and the auxiliary circuits.

Fig; 4is a sectional sideelevation showing a detail co 'istruction of one form of in the fine quality of.

Referring to the drawings, 10 designates .a' portable receptacle which is preferably in box-form with 'a. cover 11 hinged thereto at .12, the same being provided with a handle 13 by which the whole apparatus may be readily carried about in the hand 'of the operator, :the cover being provided for locking the lid closed.

with suitable hooks (not shown) adapted to engage the pins 14 onthe. front In this box is mounted a. transformer 15' preferably of'the usual variable type for changing the alternating .to the 'direct'a nd by which the intensity'of'this current may .be nicely regulated.

Above this transformer I have placed a deck 16 in the casing on which is conveniently mou'nt edftjhevarious switches by which the-characterl or intensity of the curof the box .rent delivered'to the engraving pencil and to the work may be easily oontro led.

i In this construction, switch 18 controls the heavy current while switch-l9 controls the light current, which currents are arranged to flow from the transformer through wires.

'20 and'2l respectively and through wire-22 to the engraving pencil 23. The switches I 24:, 2'5, 26 and 27 are for the purpose of controlling four different intensities'of'current,

so. that the one desired may. be causedfto flow -from. tl1e transformer to the work platen 28 through'the main circuit .wire 29. 1

By this arrangement when the, lightest-cut is'desired on the work 30,- or' where the To obviate this 'difliculty, which is found" to be quite objectionable where fine work is desired, I have provided a second circuit engraving pencil having ine'ans therein for...- maklng and breaking the main circuit at work itself offers-I thev minimum resistance,

switches 19 @0124 are the only ones that p are closed, but when the heaviest cut is .desired, or when the work oifersthefmaximum resistance, sw'itcheslB' and27 are the only upon raising the pencil from the Work an switches closed, intermediate intensities being obtainedthrough switches-2 5'and '26; g

In' some instances it is found .particu;

larly' where the heavier current is'used that; 10 0 electric arc 'is established, which pits or. mars the work rendering it imperfect.

which is arranged to be opened and closed. I

oil. This secondary circuit isarran'ged' to control the prima'ry circuit as: follows:

-b means'of the-press button-'31 in-the-pe'n-- button 31 is depressed the bridge-member 42 completes the circuit through the wires 43 and 44, energizes the magnets 39 to with-.

draw the armature 36 and so breaks the main circuit between the contacts 34 and 35. This breaking of the main circuit is done before the point of the pencil is raised from the work thus effectually preventing the arcing at the pencil point and injurin the work.

hese circuit-breaking magnets and contact points 34 and 35 are preferably mounted in the small inclosin is secured to the main receptacle by screws 46 thus rendering this mechanism quite accessible and providing a unitary structure capable of being readily carried about from place to place in the hand of the operator.

A plug 47 which may be readily connected to the source of electric energy .is connected to wires 32 and 33 of the mam circuit.

I do not wish to be restricted to the connecting of an auxiliar circuit to the pencil as in some instances t is pencil may. be op erated quite satisfactorily without the use of such auxiliary circuit when used in connection with the mechanism above described.

Iclaim: 1. An'electric engraving apparatus comprising a main circuit, a work-support and an engraving pencil in said circuit, an

case member which,

1,2 se,ooo

auxiliary circuit, and means whereby said auxiliary circuit may be caused to break said main circuit when desired.

2. An electric engraving apparatus comprising a main circuit, a work-support and an engraving pencil in said circuit, an auxiliary circuit, and means in said pencil whereby said main circuit may be broken through said auxiliary circuit.

3. An electric engraving apparatus comprising a portable receptacle inclosing an electric current transformer, a plurality of switches in said receptacle for controlling the intensity of the current to be applied to the work, a work-support of conducting material, a conductor leading to said work support, an engraving pencil, a conductor leading to said pencil and a conductor adapted to be connected to the source of electric supply.

4. An electric engraving apparatus comprising a portable receptacle in which is mounted a transformer for the main electric current and a plurality of switches for controlling the intensity of the current to be applied'to the work, a work-support electrically connected from said transformer through said switches, an electric engraving pencil electrically connected from said transformer, an auxiliary circuit, and means in said pencil whereby said latter circuit may be caused to either'make or break the maln circuit through said pencil and worksupport.

In testimon whereof I afiix my signature in presence 0' two witnesses.

' ANDREW M. ROBINSON. Witnesses:

HOWARD E. BARLow, A. F. MACREADY. 

